Cable might ask: Where’s the love?

Remember back a few years ago, when it sometimes looked like HBO and its cable brethren would forever dominate Sundays with edgy series such as “The Sopranos,” leaving just scraps to broadcast rivals? Well, this season has pretty much exploded that myth.

On Sunday, “Sopranos” averaged 7.9 million total viewers, its lowest figure for an original episode in more than five years, according to figures released Tuesday by Nielsen Media Research. And that was no fluke. In this, its sixth season, HBO’s mob drama is averaging 8.8 million total viewers, a drop of 10% compared with the fifth season. True, these numbers are still huge by cable standards, but “Sopranos” is a long way from the fourth season opener in September 2002, which logged a record 13.4 million viewers.

And Tony Soprano and his crew aren’t the only ones feeling the pain on premium cable. “Big Love,” HBO’s heavily promoted polygamy drama, looks destined to join a list of provocative, well-produced dramas -- including “Carnivale” and “Rome” -- that can’t quite reproduce “Sopranos’ ” early pop-cultural impact. Through six airings after “Sopranos,” “Big Love” is averaging 3.9 million viewers -- an impressive number for basic cable, perhaps, but far less attention than HBO had grown used to. Worse, many subscribers obviously aren’t sticking around once “Sopranos” ends.

But HBO executives can count their blessings that they don’t suffer from Showtime’s problems. “Huff,” the quirky drama with Hank Azaria, received an enormous print ad campaign designed to build awareness for the second season. But the show is clearly going nowhere. “Huff” is averaging 280,000 total viewers in three airings -- considerably less than what Bravo or VH1 typically expects for an inexpensive reality offering.

What’s the problem? At Showtime, the troubles are nothing new; the network has been perspiring in the shadow of its better-known competitor for years. HBO -- which downplays ratings because, like Showtime, it does not sell advertising -- is a different story. With “Sex and the City” and “Sopranos,” the network briefly made it look easy to find series that seemed to encapsulate the culture at a certain moment. It seemed that HBO chief Chris Albrecht and his team had discovered some kind of magic bullet. The reality, of course, is that such gold strikes are so rare that many writer-producers (and executives) spend their entire careers in a futile grasp for them. Is it possible that maybe everything does, in the end, even out?

It’s natural, in the meantime, to wonder where all those Sunday viewers have gone. The best guess is that many have migrated to ABC, which despite some cooling in the “Desperate Housewives” phenomenon has seen its Sunday ratings in the crucial adults aged 18 to 49 demographic soar 23% compared with last season. Much of that is due to this season’s show of the moment, “Grey’s Anatomy.”

And so the TV cycles continue.

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Channel Island is a blog about the television industry. For the latest posting, go to latimes.com/channelisland. Contact reporter Scott Collins at channelisland@latimes.com.